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Thread: Tachometer, Mileage gauge, and temp gauge not working! HELP!

  1. #1
    Join Date
    Mar 2017
    Location
    Connecticut
    Posts
    1
    My Cars
    1991 BMW 325i Coupe

    Tachometer, Mileage gauge, and temp gauge not working! HELP!

    Hi all,

    I have a 1991 e30 325i coupe with a Motometer Instrument Cluster thats been giving me a bit of trouble since I bought it at the beginning of March. The tachometer, economy/mileage gauge, and temperature gauge only work intermittently. I'd say the tach and economy gauge work randomly ~10 percent of the time and the temp works most of the time. When they are working they function normally. I have taken some steps to repair it with no luck thus far. Also, the OBC isn't really working just flashes HR and some dashes, doesn't light up day or night. I only make it out with the sun shining directly on it.

    First, I replaced the batteries in the SI board and a capacitor. Nothing.

    Then today, I re-soldered a small point on the board that was slightly damaged by some screw. Nothing- except now the temp gauge that was working is now out and the SI board is showing two green lights all the time even with the ignition off and the key out.

    I also had a really good electrician take a look at it and the board's capacitors and batteries were fine. Then we checked the blue connector that controls those functions and tested the following pins as indicated in my Bentley manual. 23 and ground (blue), 14 and ground (blue), which tested fine, then 2 and ground (blue)- which for some reason wasn't even in the 2 pin. --could this be the source of my problem or it is simply a discrepancy between my 1991 Motometer cluster and the Bentley manual, which conveniently only goes to 1990?


    If you have any idea as to what I can do to make this tach and temp gauge work that would be much appreciated.

    Please don't just tell me to buy another board or instrument cluster, unless you really think it will solve my problem for good. Im looking for other cheaper solutions/things to check before I resort to purchasing a new cluster.

    Thanks for the help!
    Last edited by nphoff; 03-18-2017 at 01:33 AM. Reason: Forgot something

  2. #2
    Join Date
    Mar 2017
    Location
    Nowhere
    Posts
    223
    My Cars
    something
    First, try to reset the SI board. http://www.billswebspace.com/BMWE30....0the%20SIL.htm If it does not reset then the board could definitely be the problem. The fact that the lights are staying on tends to lead in that direction. You could try to reroute pin 2 since that is the cheapest way. Mine was beyond repair due to corrosion (still tried to resuscitate it) and I had buy a new board.

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